Lactation Physiology

    This article explains the physiology of lactation – hormonal changes preparing breasts during pregnancy and promoting milk production after delivery, and regulation of milk production according to baby’s demands.


    Important Points

    hormones prepare breasts to produce milk
    • Lactogenesis I is the stage of maturation of breasts under hormonal control during pregnancy.
      • Progesterone, prolactin, and placental lactogen increases the number of alveoli
      • Estrogen and growth hormone increases the number of milk ducts
    • Lactogenesis II is the stage of copious milk secretion 36-48 hours after birth because of:
      • Fall in progesterone levels
      • Prolactin hormone
      • Early and frequent breastfeeding
      • Cortisol and insulin hormone
    • Lactogenesis II is called delayed if happens after 72 hours. Delay in lactogenesis II can be prevented by:
      • Direct breastfeeding
      • Frequent and exclusive breastfeeding
      • Initiation of breastfeeding within one hour of birth
    • Prolactin is the main hormone for milk production and its levels increase when the baby breastfeeds.
    • Metoclopramide and domperidone increase breast milk production by increasing prolactin levels.
    • Oxytocin hormone causes ‘let down’ of breast milk.
    • Lactogenesis III is the stage of maintenance of milk production.
    • Feedback inhibitor of lactation is secreted in alveoli when they are full of milk. It inhibits further milk production.
      • Frequent emptying of breasts –> more milk production
      • Full breasts –> decreases milk production

    Related articles: Breast Anatomy


    1. Widström AM, Wahlberg V, Matthiesen AS, Eneroth P, Uvnäs-Moberg K, Werner S, Winberg J. Short-term effects of early suckling and touch of the nipple on maternal behaviour. Early Hum Dev. 1990 Mar;21(3):153-63. doi: 10.1016/0378-3782(90)90114-x. PMID: 2311552.
    2. Matthiesen AS, Ransjö-Arvidson AB, Nissen E, Uvnäs-Moberg K. Postpartum maternal oxytocin release by newborns: effects of infant hand massage and sucking. Birth. 2001 Mar;28(1):13-9. doi: 10.1046/j.1523-536x.2001.00013.x. PMID: 11264623.
    3. Moore ER, Anderson GC, Bergman N. Early skin-to-skin contact for mothers and their healthy newborn infants. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD003519. doi: 10.1002/14651858.CD003519.pub2. Update in: Cochrane Database Syst Rev. 2012;5:CD003519. PMID: 17636727.
    4. Anderson GC, Moore E, Hepworth J, Bergman N. Early skin-to-skin contact for mothers and their healthy newborn infants. Cochrane Database Syst Rev. 2003;(2):CD003519. doi: 10.1002/14651858.CD003519. Update in: Cochrane Database Syst Rev. 2007;(3):CD003519. PMID: 12804473.
    5. Neubauer, Suzanne & Ferris, Ann & Chase, C & Fanelli, J & Thompson, C.A. & Lammi-Keefe, Carol & Clark, R & Jensen, R & Bendel, R & Green, K. (1993). Delayed lactogenesis in women with insulin-dependent diabetes mellitus. The American journal of clinical nutrition. 58. 54-60. 10.1093/ajcn/58.1.54.
    6. Boss M, Gardner H, Hartmann P. Normal Human Lactation: closing the gap. F1000Res. 2018 Jun 20;7:F1000 Faculty Rev-801. doi: 10.12688/f1000research.14452.1. PMID: 29983914; PMCID: PMC6013763.

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